We're a fickle bunch these days, with news of so-and-so's fresh carbon rim not causing the hubbub it once did. We get it; it's light and black and carbon and expensive and probably not worth the price when you really think about it. And when it comes to aluminum rims... I've got a freshly painted wall that I need to watch dry, thank you very much.
But Spank Industries - who've always shunned carbon fiber - are doing some genuinely interesting things with their aluminum rims, especially the part where they fill them with green foam that hardens up. More interesting than you thought, right? Yeah, these aren't your run of the mill alloy hoops.
Spike 350 Vibrocore Wheelset
• Intended use: trail / all-mountain / enduro
• Diameter: 27.5'' or 29'' (tested)
• Rim width: 30.5mm (inner)
• Vibrocore foam-filled rim cavity
• Hub Compatibility: All of 'em
• Tape and valve included
• Weight: 2,078-grams (29'')
• MSRP: $699 USD
• More info: www.spank-ind.com
The green foam is the Vibrocore in Spank's Spike 350 Vibrocore wheelset and the claim is that it's there to help with vibration damping. The $699 USD, 2,078-gram wheelset is made for everything from trail riding to downhill use, and you can get 'em in both 27.5'' and 29'' sizes.
With a low height and thinner walls, the 350 Vibrocore rim is said to offer more vertical compliance.Design
You don't need to be a marketing scientist to know that having a long list of features is gonna help you sell whatever it is you're hoping people buy. Truth is, however, that a lot of those cleverly named features don't really add up to much more than that, just another bullet point in the catalog.
But whether it works as claimed or not, Spank's Vibrocore foam-filled rim design is more than just a bullet point. In fact, it might be the most interesting thing to happen to aluminum hoops since someone figured out how to design them with more than a single wall.
The foam goes in soft but then hardens up as it dries.
Here's the claim. First, we're supposed to stop calling it 'just' foam. It's a ''Proprietary, biodegradable, complex foam core of precisely controlled density,
'' and Spank says that it ''Reduces vibrations or ‘noise’. The low density, pressurized core performs a similar function to the soft tissue inside bones, increasing inner wall strength and absorbing vibrations.
'' This, along with the rim's relatively low height, is supposed to make for a wheel that's able to damp certain types of vibrations better than a traditional design.
The Vibrocored Oozy 350 rim comes in at a still respectable 545-grams in the 29'' size, or just 40-grams more than the standard Oozy hoop. Foam doesn't weight much. It also adds about $30 USD to the cost, with the stuffed 350 going for $129 USD on its own.
Spank's been doing some clever things with aluminum, and in their own factory, for many years now. One of them is the 'W' cross-section to the rim that's said to increase strength over the traditional 'U' shape; think corrugated sheets of aluminum and you'll get the idea.
The other neat bit worth pointing out are the three rows of 0.2mm tall ridges that run the length of the rim's sidewall and bed - you can spot them in the photo below. You've probably already figured out what's going on: More friction between these ridges and the tire's bead should mean fewer burps. Spank says that it helps to do that for both tubed and tubeless setups, too.
Spot those ridges on the rim's sidewall? They're supposed to help keep the tire from burping or unseating entirely.
The rest of the Spike 350 Vibrocore wheelset is pretty straightforward. There are 32 triple butted, J-bend spokes laced three-cross (and 32 brass nipples) to a set of nice looking hubs that turn on sealed bearings. You can choose between XD or a normal freehub, and inside there's a conventional three-pawl, steel drive-ring setup that you get at by using a 17mm cone wrench on one side and the handle of another wrench into the axle slots
on the other.
Spank has done their customers a solid by not just making sure the hubs can fit everything from quick-release 100/135mm to all the different thru-axle options, but they've also laser etched each designation onto the caps. I have a drawer full of hub parts that I'll probably never use because I don't have the slightest clue what they fit, so I like this simple detail.
The hubs are straightforward, and the interchangeable endcaps are laser etched so you'll always know what axle size they fit.Performance
So, does this green stuff actually make a difference or is it just there for the bullet points? The 350 Vibrocore wheels were bolted onto a Trek Slash owned by someone who goes through alloy rims quicker than I go through tires, which is absurd. Yeah, Squamish, BC, isn't easy on bike gear. Reliability and feel are the questions here, though, so it's an ideal location.
The Vibrocore guts don't make this rim indestructible, but they did brush off the kind of abuse that claimed a handful of other rims over prior months. Giant dents, flat spots, and cracks took out the others, but the 350s lasted longer than any other wheel, especially the one on the back of the bike. Not only did the rear wheel stay relatively true, the rim's sidewalls didn't fold over like cardboard when it was smashed into the backside of a rock. That's a win in my books.
It wasn't all smooth sailing, though, with the rear wheel needing a re-tensioning after just three rides and then some more love required four weeks down the road. That said, the rim was still straight and dent-free, but the build definitely required a few spins of the spoke wrench to bring the tension back up. Keep in mind that it'd be around this time that any other aluminum rim that's been on the back of this bike would go into the bin, but the 350 hoops kept on trucking.
It's also worth noting that there were less burping incidents compared to other alloy rims, be it through a hard corner or a sideways landing, so maybe there's something to Spank's funky ribbed sidewalls. I always like it when my tire doesn't come off mid-ride.
The 350s stood up to some serious abuse, lasting longer than any other aluminum rim that one particular test rider has ever used.
Feel is the other talking point, with Spank saying that the design offers a degree of radial compliance, presumably more than your average carbon rim. This one's a bit more ambiguous, however, and especially when they're attached to a supple, active enduro race bike. One bit of feedback that does stand out is that they felt a bit "dead," for lack of a better term, which could be the foam core doing what it's supposed to be doing. Either way, they were much more reliable than other wheels that have seen the same abuse.
The hubs proved to be trouble-free as well, and while they eventually needed some love, aka a re-tensioning, the 350s were more reliable than any other wheelset that's called that Slash home.Pinkbike's Take: